The shout went up from a posse of children as they raced past the health clinic in a valley deep in the Papua New Guinean highlands. Inside, Swiss-born nurse and nun Sister Gaudentia Meier — 40-something years and a world away from the ordered alps of her homeland — was getting on with her daily routine, patching the wounds and treating the sicknesses of an otherwise woefully neglected population. It was around lunchtime, she recalls.

Sister Gaudentia knew immediately the spectacle the excited children were rushing to see. They were on their way to a witch-burning. There are many names for dark magic in the 850 tongues of Papua New Guinea, sanguma resonating widely in these mountains. The 74-year-old sister hurriedly rounded up some of her staff, loaded them in a car and followed the crowd, with a strong foreboding of what she would find.

Two days earlier she had tried to rescue Angela (not her real name), an accused witch, when she was first seized by a gang of merciless inquisitors looking for someone to blame for the recent deaths of two young men. They had stripped their quarry naked, blindfolded her, berated her with accusations and slashed her with bush knives (machetes). The “dock” for her trial was a rusty length of corrugated roofing, upon which she was displayed trussed and helpless. Photographs taken by a witness on a mobile phone show that the packed, inert public gallery encircling her included several uniformed police.

In Papua New Guinea, the Pacific nation just a short boat ride from Australia’s far north, 80 per cent of the 7 million-plus population live in rural and remote communities. Many have little access to even basic health and education, surviving on what they eat or earn from their gardens. There are few roads out, but a burgeoning network of digital-phone towers and dirt-cheap handsets now connect them to the world — assuming they can plug into power and scrounge a few kina-worth of credit.

The resources-rich country is in the midst of a mining boom, but the wealth bypasses the vast majority. In their realities, some untouched by outside influence until only a couple of short-lived generations ago, enduring tradition widely resists the notion that natural causes, disease, accident or recklessness might be responsible for a death. Rather, bad magic is the certain culprit.

Last year, a two-year investigation by the country’s Constitutional and Law Reform Commission observed that the view that sorcery or witchcraft must be to blame for sickness or early death is commonly held across PNG.

Many educated, city-dwelling Papua New Guineans also espouse some belief in sorcery. But in the words of the editor of the national daily Post Courier, Alexander Rheeney, city and country-folk alike overwhelmingly “recoil in fear and disgust” at lynch-mobs pursuing payback, and at the kind of extremist cruelty that Sister Gaudentia was about to witness.

Angela’s accusers — young men from another town, high on potent highlands dope and “steam” (home-brewed hooch) — had come back for her. Sister Gaudentia suspected the same mob had tortured a young woman she nursed a few months earlier. She had dragged herself, “how … I don’t know”, says the nun, into the clinic, her genitals burned and fused beyond functional repair by the repeated intrusions of red-hot irons.

The concept of a serial-offending torture squad hunting down witches doesn’t fit the picture anthropologists have assembled of the customs that underwrite sorcery “pay-back” in parts of PNG. Attacks are, as a general rule, the spontaneous act of a grieving family, inspired often by vengeance, and sometimes by fear that evil magic will be exercised again. But experts also concede there are caveats to every rule in PNG. One of the most ethnically diverse landscapes in the world, PNG is endlessly confounding to outsiders, and even as modern explorers strive to pin down aspects of the old world, it changes before them.